The invention relates to methods for optionally dispensing, receiving or storing semiconductor devices including integrated circuits and, more specifically, to methods employing vertical stacking of such devices in magazines.
As the semiconductor industry advances in the fabrication and processing of packaged semiconductor devices (sometimes referred to herein for convenience as "devices"), such as thin small outline packages, or TSOPs, testing and sorting of such devices pose challenges in terms of device throughput, test equipment space utilization, and device distribution responsive to test result-responsive sorting.
Currently, processing of thin package devices such as TSOPs is primarily carried out based upon specialized JEDEC (Joint Electronic Device Engineering Council)--specification trays, which are approximately five inches wide by twelve inches long. The JEDEC tray design dictates that the semiconductor devices are carried in a single layer, arranged in mutually perpendicular rows and columns. Tray density, or the number of devices carried by each tray, obviously decreases as device size increases. For reference purposes, if a given device is 0.400 inch wide by 0.750 inch long, a JEDEC tray part capacity, with a nine row by thirteen column configuration, is about 117 parts per tray.
Testing of the devices is conventionally carried out in batches of thirty-two parts (devices) run through a test cycle simultaneously. The devices are then sorted into a number of categories based upon test results and then "binned" into the aforementioned JEDEC trays by a conventional "pick-and-place" robotic arm system. At the present time, as many as sixteen sort categories are employed, and it is anticipated that the number of sort categories will increase as the sophistication and miniaturization of semiconductor devices continue in the future. If each JEDEC tray employed for receiving post-test devices is intended to receive a single bin or sort category, a substantial amount of manufacturing floor space is required to accommodate an arrangement where sixteen JEDEC trays are placed in a horizontal array. Further, the size and complexity of the pick-and-place device required to place tested devices in the trays of such an array become unreasonable. Alternatively, if (for example) sixteen JEDEC trays are stacked in a holding tower in a vertical format, wherein the trays themselves are again horizontally oriented but mutually vertically superimposed, a tray retrieval and presentation mechanism is required. Further, the time to retrieve each tray from the tower, present it for pick-and-placement of a tested device, and replace the tray in the tower severely limits device throughput. As the number of sort categories increases, each of the foregoing approaches to device binning becomes ever-more unwieldy to execute.
Thus, the prior art approach to semiconductor device sorting and binning has demonstrated severe deficiencies in terms of throughput, space utilization, and complexity of required device handling equipment.